1. Field of the Invention
The present disclosure relates to an orthodontic field, more particularly to an automated system capable of accurately positioning orthodontic brackets on the patient's tooth surfaces or surfaces of a dental model.
2. Description of the Related Art
In orthodontic dentistry, it is found that the malocclusion of teeth affects development of normal function of the patient's mouth and reduces mastication efficiency of teeth, which results in problem of swallowing, indigestion and gastrointestinal disease. Severe tooth misalignment also affects growth of facial skeleton, temporo-mandibular joint and muscle, and causes facial asymmetry and undesirable language expression. Therefore, a negative effect may be produced on the patient's psychology. The maxillary and/or mandibular protrusion may cause that lips cannot be closed freely and undesirable mouth breathing. The oral plaque may be easily attached on misaligned dentition and hardly cleaned, so it easily causes dental decay, gingivitis and periodontitis.
Malocclusion is caused by the problem of the misaligned teeth or undesirable jaw relation. The orthodontic braces or brackets can be fastened on the tooth surface in order to fully achieve orthodontic effect. Brackets are bonded on tooth surfaces one by one, metal wires are engaged in the brackets, and the metal wires interact with the brackets to move the teeth into the desired positions.
Clinically, the bonding positions and orientations of the brackets relative to tooth's axes are highly depended on experiences and skills of dentists. The procedure of bonding the brackets on the tooth surfaces can be accomplished in two ways: direct and indirect bonding procedures. In the direct bonding procedure, the dentist bonds the brackets on the tooth surfaces one by one upon his/her experience and skill, but it consumes much chair time of the dentist. In addition, some regions inside the mouth (such as molar teeth or lingual surface of tooth) can hardly be visually accessed by the dentists that make the bracket bonding work difficult. The indirect procedure requires the patients' impression model taken by the dentist, and dental casts similar to patients' dentitions can be made based on the impression model. The dental technicians then bond the brackets on the dental casts in the laboratory. The positions of the bonded brackets will be recorded by using a custom impression tray. Clinically, the dentists can then transfer the position records and bond the brackets on patients' teeth.
Currently, the use of digital model is rapidly increasing in the orthodontic industry. The so-called digital model is a 3D digital dental cast which is constructed by using patient's intra-oral scan, computation, analysis and modeling, and the 3D digital dental cast can be transformed to a physical dental cast by a well-known technology (such as 3D printing). For dentist, the digital model is helpful for more correct dental diagnosis and orthodontics treatment planning, and also useful for predicting or simulating movements of the teeth and treatment result during the treatment.
The digital model can provide assistance however, each step of bonding the brackets on teeth by the direct bonding procedure or the indirect bonding procedure is still executed by the dentist. Actually, it is a difficult work. First, some regions (such as tooth at deep part of oral cavity or lingual surface) are hardly visible and touched. Next, bonding materials are time- and light-sensitive that they should be skillfully handled. The light-curing adhesive is adopted as the adhesive for bonding material and should be hardened not until the bracket is positioned correctly. If the material is hardened too early, it will have insufficient time for the brackets to be placed correctly. The brackets will be bonded at unexpected positions. Therefore, controlling the adhesive curing time is a challenge for dentist. Moreover, severe misaligned teeth may increase difficulty on positioning and fastening of the brackets, and cause the procedures hardly be achieved perfectly.